I've got an article up on Curbside Classic about the three(!) different developmental versions of the diesel 225.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Cool Stuff as usual Dan!

Thanks for Sharing.

Greg

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http://www.youtube.com/hyperpack

Nice! Can't wait to read that one Dan. Thanks for sharing.

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DynoDave
1970 Plymouth Duster
1972 Dodge Charger Rallye
1977 Chrysler Cordoba
WPC # 12304

Nice! Thank you very much for your careful work, Dan. Very cool pics and factory materials in there too. Neat that they raised the intake port so much on the revised head.

Lou

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Home of Slant6-powered fun machines since 1988

Nice article.

Good thing they never actually released it....mighta been another Olds 350 diesel scandal that woulda tarnished the Slant Six reputation.

I suspect what they learned with this project helped guide them toward choosing the Cummins for their pickups.

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Good point.

Great article!

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Casually looking for a Clifford hyperpak intake for cheap.

Excellent Dan!

The raised intake port is basically how I'd like to see for a alloy slant six head! The Olds diesel might have caused slow sales at first but if the 225 diesel was good, it would have earned its own reputation. My question is how quick a diesel powered Chrysler vehicle might have accelerated. Would it had been as quick as a 300D? Slow and good is fine with me!

The Olds diesel could have been much better if they had delayed the project and tested with fleets for a longer time period, then not built so many of them at first. The owners should have been given at least a 15 minute lecture of proper maintenance. Common diesel problems and solutions aren't a mystery. I'm sure there were internal engineering memos warning of everything that would ruin the reputation of this motor. GM customers of cushy big cars were probably not the best target market for initial use. The Mercedes OM617 was bulletproof and costly to build and that kind of reliability is what GM owners expected, but didn't pay for. But they deserved better than they got. A few upgrades wouldn't have made it a great motor, but it could have been relatively reliable for what it was. There are a few 5.7 diesel owners who care for them and boast of long life, just to be quirky I suppose. Rebuildable cores are actually sought after.

I seem to recall the key issue was blamed on trying to fit a diesel head (and all that goes with it) onto a gas block.

An engineer I worked with bought one, new. As you note, he was a 'comfort' driver. It was in the shop almost immediately...back and forth for several months....and the end result was something major cracked apart and he wound up driving some other car. A complete disaster.

Scroll down thru the comments on the article and you'll see where I derive an approximation of the torque and horsepower figures for the turbodiesel 225. Search the page for the word math.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

That was a very well written article; thanks Dan!

Seems that exhaust manifold (if made in high enough numbers) might possibly have been an idea for turbocharging a gasoline engine with EFI. Fitting an intercooler and piping may be interesting, but I'd be keen to hook my peepers on one of those exhaust manifolds for dang sure!

~THOR~

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
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Part of Tyrde-Browne Racing

The Olds block was machined on the same tooling that processed the gasoline V8 blocks but it was a heavier casting, particularly the last series. It was a high compression na diesel and water in the fuel caused extreme combustion pressures from steam, which stretched the head bolts. The water in the fuel also destroyed the injection pumps and broke crankshafts. The head gaskets were inadequate. Replacing the head bolts with stronger ones and filtering the water from the fuel allows them to survive, but GM management was slow to order a recall and a proper fix. Considering the 5.7 was in production for almost 7 years GM had many opportunities to fix basic issues, and many problems were resolved, but they became difficult to sell. Many GM dealerships swapped them for gasoline versions when they could have repaired them, most dealer mechanics were poorly trained on diesels. The v8 only made 125 hp, but had decent torque. GM sold over 300,000 of them in 1981. Many were used with the 200 Metric series automatic which developed a troublesome reputation. Some claim the 4.3 v6 diesel didn't have many of the problems that the 5.7 v8 did as it was released later. It might have been the beginning of the end not just for diesels, but large American sedans.

With the proper development a diesel 225 could have been a decent truck motor. The K-car and derivatives ended rear drive passenger car development as a fuel economy target. Many swap the 800 pound 105 hp Cummins 3.9 liter 4BT into pickup trucks, that motor is durable but its not that good. Widely admired and durable - conservative - the 4BT has adequate torque, but its hardly state of the art. The 4BT is agricultural. If Dodge truck officials could have predicted how popular the 6BT would become, maybe they would have designed a new Dakota to use a slant six diesel? I have doubts that Ram would have been as popular today without the Cummins association, but at the time the Cummins was supposed to make up for the loss of the big block V8 after 1978 - Chrysler didn't have a commercial duty engine and '80s truck sales suffered because of it.

Some Mercedes passenger diesels were also produced in gasoline versions using the same block. Its a matter of development and testing, and testing, and testing. But those advanced Mercedes diesels are more than a decade later than the era of the slant six diesel. Check out the OM606, last built in 2001. Its a 3 liter inline six rated at 174 hp and weighs just 465 pounds. Years into the future for this topic, but you have to start somewhere.

Why did the B series Cummins have to be so heavy ? It was designed for heavy equipment. Even today the 6.7 is widely used in industrial equipment where heavy weight isn't a factor.

We've been taught to respect 'engineering' and 'computers' and 'finite element analysis' and all sorts of higher learning when it comes to mechanical equipment. All of which is good, but one thing is for sure....adding iron/steel to just about anything is a fast way to make it more durable.

The diesel engine....a good engine in many ways, but without the turbocharger, it would be a farm equipment piece only.